[RFC PATCHv2 01/20] ARM: architected timers: move local timer support to percpu_timer.c
Marc Zyngier
marc.zyngier at arm.com
Tue Mar 15 11:12:44 EDT 2011
To introduce the A15 architected timers without causing too
much disruption on the rest of the kernel, introduce percpu_timer.c
to act as a registration interface that the platform can call at
runtime.
Timer functions are moved out of smp.c (as the A15 can use the
local timer in UP configuration) and smp_twd.c now returns
a set of operations that percpu_timer.c can call.
Acked-by: Catalin Marinas <catalin.marinas at arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
---
arch/arm/Kconfig | 6 +-
arch/arm/include/asm/entry-macro-multi.S | 2 +-
arch/arm/include/asm/localtimer.h | 60 +++++++----
arch/arm/include/asm/smp.h | 7 +-
arch/arm/include/asm/smp_twd.h | 27 ++++-
arch/arm/kernel/Makefile | 1 +
arch/arm/kernel/irq.c | 1 +
arch/arm/kernel/percpu_timer.c | 164 ++++++++++++++++++++++++++++++
arch/arm/kernel/smp.c | 92 +----------------
arch/arm/kernel/smp_twd.c | 29 +++++-
10 files changed, 266 insertions(+), 123 deletions(-)
create mode 100644 arch/arm/kernel/percpu_timer.c
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 93d595a..b7e504b 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1326,6 +1326,7 @@ config SMP
ARCH_MSM_SCORPIONMP || ARCH_SHMOBILE
select USE_GENERIC_SMP_HELPERS
select HAVE_ARM_SCU if !ARCH_MSM_SCORPIONMP
+ select HAVE_ARM_TWD if (!ARCH_MSM_SCORPIONMP && !EXYNOS4_MCT)
help
This enables support for systems with more than one CPU. If you have
a system with only one CPU, like most personal computers, say N. If
@@ -1407,10 +1408,9 @@ config HOTPLUG_CPU
can be controlled through /sys/devices/system/cpu.
config LOCAL_TIMERS
- bool "Use local timer interrupts"
- depends on SMP
+ bool
+ depends on SMP || ARCH_MSM_SCORPIONMP
default y
- select HAVE_ARM_TWD if (!ARCH_MSM_SCORPIONMP && !EXYNOS4_MCT)
help
Enable support for local timers on SMP platforms, rather then the
legacy IPI broadcast method. Local timers allows the system
diff --git a/arch/arm/include/asm/entry-macro-multi.S b/arch/arm/include/asm/entry-macro-multi.S
index ec0bbf7..589d4ef 100644
--- a/arch/arm/include/asm/entry-macro-multi.S
+++ b/arch/arm/include/asm/entry-macro-multi.S
@@ -23,6 +23,7 @@
movne r1, sp
adrne lr, BSYM(1b)
bne do_IPI
+#endif
#ifdef CONFIG_LOCAL_TIMERS
test_for_ltirq r0, r6, r5, lr
@@ -30,7 +31,6 @@
adrne lr, BSYM(1b)
bne do_local_timer
#endif
-#endif
9997:
.endm
diff --git a/arch/arm/include/asm/localtimer.h b/arch/arm/include/asm/localtimer.h
index 080d74f..8988c50 100644
--- a/arch/arm/include/asm/localtimer.h
+++ b/arch/arm/include/asm/localtimer.h
@@ -10,7 +10,9 @@
#ifndef __ASM_ARM_LOCALTIMER_H
#define __ASM_ARM_LOCALTIMER_H
-struct clock_event_device;
+#include <linux/clockchips.h>
+
+struct seq_file;
/*
* Setup a per-cpu timer, whether it be a local timer or dummy broadcast
@@ -18,40 +20,58 @@ struct clock_event_device;
void percpu_timer_setup(void);
/*
- * Called from assembly, this is the local timer IRQ handler
+ * Call a per-cpu timer handler
*/
-asmlinkage void do_local_timer(struct pt_regs *);
-
-
-#ifdef CONFIG_LOCAL_TIMERS
-
-#ifdef CONFIG_HAVE_ARM_TWD
+void percpu_timer_run(void);
-#include "smp_twd.h"
-
-#define local_timer_ack() twd_timer_ack()
-
-#else
+/*
+ * Stop a per-cpu timer
+ */
+void percpu_timer_stop(void);
/*
- * Platform provides this to acknowledge a local timer IRQ.
- * Returns true if the local timer IRQ is to be processed.
+ * Called from assembly, this is the local timer IRQ handler
*/
-int local_timer_ack(void);
+asmlinkage void do_local_timer(struct pt_regs *);
-#endif
+struct local_timer_ops {
+ void (*const pre_setup)(struct clock_event_device *clk);
+ int (*plat_setup)(struct clock_event_device *clk);
+ void (*const setup)(struct clock_event_device *clk);
+ int (*const ack)(void);
+};
+#ifdef CONFIG_LOCAL_TIMERS
/*
* Setup a local timer interrupt for a CPU.
*/
int local_timer_setup(struct clock_event_device *);
+/*
+ * Register a local timer.
+ */
+void percpu_timer_register(struct local_timer_ops *);
#else
-
-static inline int local_timer_setup(struct clock_event_device *evt)
+static inline void percpu_timer_register(void *dummy)
{
- return -ENXIO;
}
#endif
+static inline int percpu_timer_register_setup(struct local_timer_ops *ops,
+ int (*plat_setup)(struct clock_event_device *))
+{
+ if (ops) {
+ ops->plat_setup = plat_setup;
+ percpu_timer_register(ops);
+ return 0;
+ }
+
+ return -ENODEV;
+}
+
+/*
+ * show local interrupt info
+ */
+extern void show_local_irqs(struct seq_file *, int);
+
#endif
diff --git a/arch/arm/include/asm/smp.h b/arch/arm/include/asm/smp.h
index 96ed521..2e31e8d 100644
--- a/arch/arm/include/asm/smp.h
+++ b/arch/arm/include/asm/smp.h
@@ -95,9 +95,8 @@ extern void platform_cpu_enable(unsigned int cpu);
extern void arch_send_call_function_single_ipi(int cpu);
extern void arch_send_call_function_ipi_mask(const struct cpumask *mask);
-/*
- * show local interrupt info
- */
-extern void show_local_irqs(struct seq_file *, int);
+#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
+void smp_timer_broadcast(const struct cpumask *mask);
+#endif
#endif /* ifndef __ASM_ARM_SMP_H */
diff --git a/arch/arm/include/asm/smp_twd.h b/arch/arm/include/asm/smp_twd.h
index fed9981..4096736 100644
--- a/arch/arm/include/asm/smp_twd.h
+++ b/arch/arm/include/asm/smp_twd.h
@@ -1,6 +1,8 @@
#ifndef __ASMARM_SMP_TWD_H
#define __ASMARM_SMP_TWD_H
+#include <linux/clockchips.h>
+
#define TWD_TIMER_LOAD 0x00
#define TWD_TIMER_COUNTER 0x04
#define TWD_TIMER_CONTROL 0x08
@@ -18,11 +20,28 @@
#define TWD_TIMER_CONTROL_PERIODIC (1 << 1)
#define TWD_TIMER_CONTROL_IT_ENABLE (1 << 2)
-struct clock_event_device;
-
extern void __iomem *twd_base;
-int twd_timer_ack(void);
-void twd_timer_setup(struct clock_event_device *);
+#ifdef CONFIG_HAVE_ARM_TWD
+struct local_timer_ops *local_timer_get_twd_ops(void);
+int twd_timer_register_setup(int (*setup)(struct clock_event_device *));
+#else
+static inline struct local_timer_ops *local_timer_get_twd_ops(void)
+{
+ return NULL;
+}
+
+static inline int twd_timer_register_setup(int (*setup)(struct clock_event_device *))
+{
+ return -ENODEV;
+}
+#endif
+
+/*
+ * Dummy function, to be removed once there is no in-tree user anymore.
+ */
+static inline void twd_timer_setup(void *dummy)
+{
+}
#endif
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index 74554f1..277f6ff 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -34,6 +34,7 @@ obj-$(CONFIG_HAVE_SCHED_CLOCK) += sched_clock.o
obj-$(CONFIG_SMP) += smp.o smp_tlb.o
obj-$(CONFIG_HAVE_ARM_SCU) += smp_scu.o
obj-$(CONFIG_HAVE_ARM_TWD) += smp_twd.o
+obj-$(CONFIG_LOCAL_TIMERS) += percpu_timer.o
obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o
obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o
obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o
diff --git a/arch/arm/kernel/irq.c b/arch/arm/kernel/irq.c
index 3535d37..97154bc 100644
--- a/arch/arm/kernel/irq.c
+++ b/arch/arm/kernel/irq.c
@@ -38,6 +38,7 @@
#include <linux/ftrace.h>
#include <asm/system.h>
+#include <asm/localtimer.h>
#include <asm/mach/arch.h>
#include <asm/mach/irq.h>
#include <asm/mach/time.h>
diff --git a/arch/arm/kernel/percpu_timer.c b/arch/arm/kernel/percpu_timer.c
new file mode 100644
index 0000000..5992fae
--- /dev/null
+++ b/arch/arm/kernel/percpu_timer.c
@@ -0,0 +1,164 @@
+/*
+ * linux/arch/arm/kernel/percpu_timer.c
+ *
+ * Copyright (C) 2011 ARM Ltd.
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/irq.h>
+#include <linux/seq_file.h>
+#include <linux/interrupt.h>
+
+#include <asm/localtimer.h>
+#include <asm/hardware/gic.h>
+
+#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
+static void broadcast_timer_set_mode(enum clock_event_mode mode,
+ struct clock_event_device *evt)
+{
+}
+#else
+#define broadcast_timer_set_mode NULL
+#define smp_timer_broadcast NULL
+#endif
+
+static void broadcast_timer_setup(struct clock_event_device *evt)
+{
+ /* check that no-one has registered the timer in plat_setup */
+ if (evt->name)
+ return;
+
+ evt->name = "dummy_timer";
+ evt->features = CLOCK_EVT_FEAT_ONESHOT |
+ CLOCK_EVT_FEAT_PERIODIC |
+ CLOCK_EVT_FEAT_DUMMY;
+ evt->rating = 400;
+ evt->mult = 1;
+ evt->set_mode = broadcast_timer_set_mode;
+ evt->broadcast = smp_timer_broadcast;
+
+ clockevents_register_device(evt);
+}
+
+static struct local_timer_ops broadcast_timer_ops = {
+ .setup = broadcast_timer_setup,
+};
+
+static struct local_timer_ops *timer_ops;
+
+int __attribute__ ((weak)) local_timer_setup(struct clock_event_device *evt)
+{
+ return -ENXIO;
+}
+
+void percpu_timer_register(struct local_timer_ops *ops)
+{
+ timer_ops = ops;
+}
+
+/*
+ * local_timer_ack: checks for a local timer interrupt.
+ *
+ * If a local timer interrupt has occurred, acknowledge and return 1.
+ * Otherwise, return 0.
+ *
+ * This can be overloaded by platform code that doesn't provide its
+ * timer in timer_fns way (msm at the moment). Once all platforms have
+ * migrated, the weak alias can be removed.
+ */
+static int percpu_timer_ack(void)
+{
+ return timer_ops->ack();
+}
+
+int local_timer_ack(void) __attribute__ ((weak, alias("percpu_timer_ack")));
+
+asmlinkage void __exception_irq_entry do_local_timer(struct pt_regs *regs)
+{
+ struct pt_regs *old_regs = set_irq_regs(regs);
+ int cpu = smp_processor_id();
+
+ if (local_timer_ack()) {
+ __inc_irq_stat(cpu, local_timer_irqs);
+ percpu_timer_run();
+ }
+
+ set_irq_regs(old_regs);
+}
+
+void show_local_irqs(struct seq_file *p, int prec)
+{
+ unsigned int cpu;
+
+ seq_printf(p, "%*s: ", prec, "LOC");
+
+ for_each_present_cpu(cpu)
+ seq_printf(p, "%10u ", __get_irq_stat(cpu, local_timer_irqs));
+
+ seq_printf(p, " Local timer interrupts\n");
+}
+
+/*
+ * Timer (local or broadcast) support
+ */
+static DEFINE_PER_CPU(struct clock_event_device, percpu_clockevent);
+
+void percpu_timer_run(void)
+{
+ struct clock_event_device *evt = &__get_cpu_var(percpu_clockevent);
+ irq_enter();
+ evt->event_handler(evt);
+ irq_exit();
+}
+
+void __cpuinit percpu_timer_setup(void)
+{
+ int ret = 0;
+ unsigned int cpu = smp_processor_id();
+ struct clock_event_device *evt = &per_cpu(percpu_clockevent, cpu);
+
+ if (evt->name)
+ return;
+
+ /*
+ * All this can go away once we've migrated all users to
+ * properly register the timer they use, and broadcast can
+ * become the fallback.
+ */
+ if (!timer_ops)
+ timer_ops = local_timer_get_twd_ops();
+ if (!timer_ops)
+ timer_ops = &broadcast_timer_ops;
+ if (!timer_ops->plat_setup)
+ timer_ops->plat_setup = local_timer_setup;
+
+ evt->cpumask = cpumask_of(cpu);
+
+ if (timer_ops->pre_setup)
+ timer_ops->pre_setup(evt);
+ if (timer_ops->plat_setup)
+ ret = timer_ops->plat_setup(evt);
+ if (ret) /* Fallback to broadcast */
+ timer_ops = &broadcast_timer_ops;
+ if (timer_ops->setup)
+ timer_ops->setup(evt);
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+/*
+ * The generic clock events code purposely does not stop the local timer
+ * on CPU_DEAD/CPU_DEAD_FROZEN hotplug events, so we have to do it
+ * manually here.
+ */
+void percpu_timer_stop(void)
+{
+ unsigned int cpu = smp_processor_id();
+ struct clock_event_device *evt = &per_cpu(percpu_clockevent, cpu);
+
+ evt->set_mode(CLOCK_EVT_MODE_UNUSED, evt);
+}
+#endif
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 8fe05ad..b94b19c 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -153,8 +153,6 @@ int __cpuinit __cpu_up(unsigned int cpu)
}
#ifdef CONFIG_HOTPLUG_CPU
-static void percpu_timer_stop(void);
-
/*
* __cpu_disable runs on the processor to be shutdown.
*/
@@ -426,97 +424,13 @@ u64 smp_irq_stat_cpu(unsigned int cpu)
}
/*
- * Timer (local or broadcast) support
+ * Broadcast timer support
*/
-static DEFINE_PER_CPU(struct clock_event_device, percpu_clockevent);
-
-static void ipi_timer(void)
-{
- struct clock_event_device *evt = &__get_cpu_var(percpu_clockevent);
- irq_enter();
- evt->event_handler(evt);
- irq_exit();
-}
-
-#ifdef CONFIG_LOCAL_TIMERS
-asmlinkage void __exception_irq_entry do_local_timer(struct pt_regs *regs)
-{
- struct pt_regs *old_regs = set_irq_regs(regs);
- int cpu = smp_processor_id();
-
- if (local_timer_ack()) {
- __inc_irq_stat(cpu, local_timer_irqs);
- ipi_timer();
- }
-
- set_irq_regs(old_regs);
-}
-
-void show_local_irqs(struct seq_file *p, int prec)
-{
- unsigned int cpu;
-
- seq_printf(p, "%*s: ", prec, "LOC");
-
- for_each_present_cpu(cpu)
- seq_printf(p, "%10u ", __get_irq_stat(cpu, local_timer_irqs));
-
- seq_printf(p, " Local timer interrupts\n");
-}
-#endif
-
#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
-static void smp_timer_broadcast(const struct cpumask *mask)
+void smp_timer_broadcast(const struct cpumask *mask)
{
smp_cross_call(mask, IPI_TIMER);
}
-#else
-#define smp_timer_broadcast NULL
-#endif
-
-static void broadcast_timer_set_mode(enum clock_event_mode mode,
- struct clock_event_device *evt)
-{
-}
-
-static void broadcast_timer_setup(struct clock_event_device *evt)
-{
- evt->name = "dummy_timer";
- evt->features = CLOCK_EVT_FEAT_ONESHOT |
- CLOCK_EVT_FEAT_PERIODIC |
- CLOCK_EVT_FEAT_DUMMY;
- evt->rating = 400;
- evt->mult = 1;
- evt->set_mode = broadcast_timer_set_mode;
-
- clockevents_register_device(evt);
-}
-
-void __cpuinit percpu_timer_setup(void)
-{
- unsigned int cpu = smp_processor_id();
- struct clock_event_device *evt = &per_cpu(percpu_clockevent, cpu);
-
- evt->cpumask = cpumask_of(cpu);
- evt->broadcast = smp_timer_broadcast;
-
- if (local_timer_setup(evt))
- broadcast_timer_setup(evt);
-}
-
-#ifdef CONFIG_HOTPLUG_CPU
-/*
- * The generic clock events code purposely does not stop the local timer
- * on CPU_DEAD/CPU_DEAD_FROZEN hotplug events, so we have to do it
- * manually here.
- */
-static void percpu_timer_stop(void)
-{
- unsigned int cpu = smp_processor_id();
- struct clock_event_device *evt = &per_cpu(percpu_clockevent, cpu);
-
- evt->set_mode(CLOCK_EVT_MODE_UNUSED, evt);
-}
#endif
static DEFINE_SPINLOCK(stop_lock);
@@ -556,7 +470,7 @@ asmlinkage void __exception_irq_entry do_IPI(int ipinr, struct pt_regs *regs)
switch (ipinr) {
case IPI_TIMER:
- ipi_timer();
+ percpu_timer_run();
break;
case IPI_RESCHEDULE:
diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c
index 60636f4..4fdfb85 100644
--- a/arch/arm/kernel/smp_twd.c
+++ b/arch/arm/kernel/smp_twd.c
@@ -18,6 +18,7 @@
#include <linux/irq.h>
#include <linux/io.h>
+#include <asm/localtimer.h>
#include <asm/smp_twd.h>
#include <asm/hardware/gic.h>
@@ -70,7 +71,7 @@ static int twd_set_next_event(unsigned long evt,
* If a local timer interrupt has occurred, acknowledge and return 1.
* Otherwise, return 0.
*/
-int twd_timer_ack(void)
+static int twd_timer_ack(void)
{
if (__raw_readl(twd_base + TWD_TIMER_INTSTAT)) {
__raw_writel(1, twd_base + TWD_TIMER_INTSTAT);
@@ -122,7 +123,7 @@ static void __cpuinit twd_calibrate_rate(void)
/*
* Setup the local clock events for a CPU.
*/
-void __cpuinit twd_timer_setup(struct clock_event_device *clk)
+static void __cpuinit twd_setup(struct clock_event_device *clk)
{
twd_calibrate_rate();
@@ -142,3 +143,27 @@ void __cpuinit twd_timer_setup(struct clock_event_device *clk)
clockevents_register_device(clk);
}
+
+static struct local_timer_ops twd_timer_ops = {
+ .setup = twd_setup,
+ .ack = twd_timer_ack,
+};
+
+struct local_timer_ops *local_timer_get_twd_ops(void)
+{
+ if (!twd_base) {
+ pr_warn("TWD base address not set\n");
+ return NULL;
+ }
+
+ return &twd_timer_ops;
+}
+
+int __init twd_timer_register_setup(int (*setup)(struct clock_event_device *))
+{
+ if (!twd_base)
+ return -ENODEV;
+
+ percpu_timer_register_setup(&twd_timer_ops, setup);
+ return 0;
+}
--
1.7.0.4
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